This invention relates to musical instruments having electronic pickups, for example electromagnetic, piezoelectric, or microphonic. Specifically, the embodiments disclose a volume-adjustment circuit that enables separate and independent volume control in a pickup topology switch.
A musical instrument that has an electronic pickup system produces significantly different sounds depending on the pickup topology of the musical instrument. For example, in an electric guitar, a pickup topology is the wiring of the pickups in series, in parallel, in phase or out of phase, as well as wiring together different combinations of pickups, depending on the number of pickups in the guitar.
Pickup topology switches are well-known in the prior art. It is common for pickup topology switches in the prior art to use ganged, multi-pole switches to select among multiple pickup topologies on the same guitar.
Ganged switches behave like multiple independent switches tied together. Two switches are illustrated in FIG. 1: a DPDT (dual-pole, dual-throw) switch 2 and a 4P5T (four-pole, five-throw) switch 4. In DPDT 2 the view of the switch is shown in 3 dimensions, and then from beneath: the switch itself is the solid rectangle, 3-dimensional view, with six leads exiting the bottom. FIG. 1 shows that dual-throw switches are normally illustrated with common leads in the center position, and switches with a larger number of settings are illustrated with common leads at the end. The two settings of the DPDT switch are shown in 6 and 8, with electrical connections between leads indicated by thick lines. The first two settings of the 4P5T switch are shown consecutively, 10 and 12, and the fifth setting is also shown, 14. The number of throws is equal to the number of switch settings; the number of poles represents the number of independent switches that are ganged together. Ganged, multi-pole switches are used in some embodiments of the disclosed invention. The notation of switches 2 and 4 is used herein.
A prior art example of the ganged switches used to switch between different circuit topologies is illustrated in FIG. 2(a). The “on-on-on” variant of the DPDT switch, which has not two but three settings, illustrated in 16, 18, and 20, can provide combinations of series 24, parallel 28, and single-pickup 26 selections, given two pickups as input. Another prior art example, similar to the on-on-on variant of the DPDT switch is the Fender-style variant of a 5-way (1P5T) switch, illustrated in FIG. 3. The single-pole configuration is shown in FIG. 3(a); though the switch has five settings 50, 52, 54, 56, and 58 (five throws), it has one common lead 70 and three (not five) setting leads 72 74 76. Settings 1 50, 3 54, and 5 58 of the switch connect setting leads 1 72, 2 74, and 3 76 to the common pole 70, respectively. Setting 2 52 of the switch connects setting leads 1 72 and 2 74 to each other and to the common lead 70; setting 4 56 of the switch connects setting leads 2 74 and 3 76 to each other and to the common lead 70. The five settings 60 62 64 66 68 of the dual-pole configuration of the switch are illustrated in FIG. 3(b).
In prior art guitar pickup topologies, Gibson electric guitars are known, to one of ordinary skill in the art, for the “thick” sound of the electric guitar. Gibson produces this sound by wiring pickups in series. In another well-known guitar, the Fender Stratocaster, its sound is bright with bell-like harmonics, which are produced by wiring pickups in parallel, or the guitarist can switch to a single pickup, via a switch on the surface of the guitar. The Fender Stratocaster then produces a clear and “clean” sound. Custom wirings, typically produced in the lab or studio, have experimented with out-of-phase topologies as well.
Most guitarists have a number of different pickup topologies that they prefer. However, different pickup topologies can produce significant changes in volume. For example, wiring multiple pickups in series produces a much louder volume than when wiring one of those pickups alone. Wiring two pickups in parallel produces a volume similar to wiring one of those pickups alone. Wiring two pickups out of phase with respect to each other subtracts one signal from the other, thereby canceling out much of the signal and reducing volume significantly. Thus, pickup topology switches that mix different pickup topologies in the same guitar produce significant changes in output volume.
In the prior art, most guitar pickup switches limit the topology selections to those that produce similar volume levels. In particular, two of the most popular guitars, the Gibson Les Paul and the Fender Stratocaster, do not mix topologies that have different volume levels, and so in each guitar the pickup settings all have the same volume. Specifically, the Les Paul wires humbuckers (a pickup comprised of two pickups wired in series) singly or two humbuckers in parallel, both of which topologies have similar volume levels; the Stratocaster wires single pickups by themselves or two pickups in parallel, both of which topologies have similar volume levels. Both guitar designs ensure that all pickup topologies available on the guitar are volume-compatible with each other, by disallowing volume-incompatible pickup topologies. However, this volume compatibility comes at the cost of limiting the available pickup topologies and thus the sounds that each guitar can produce.
While the separation of multiple audio channels, each with its own volume setting, is used in other domains such as mixing boards and amplifiers, it has never been implemented in musical instruments having electronic pickups. There is a long felt need in the art for separate and independent volume adjustment for each pickup topology in a pickup switch used on the same musical instrument. The volume-topology problem exists in all prior art topology switches.